Step 1

Pre-heat the oven to 350 degrees. Butter a 9x13 baking dish.

Step 2

In small saucepan over low heat, melt butter completely. Stir in sugar and continue cooking for 1-2 minutes, stirring constantly. Do not allow sugar mixture to boil.

Step 3

Remove from the heat and stir in the Nutella until well combined.

Step 4

Pour butter mixture into a large bowl or stand mixer, beat in cocoa powder, eggs, salt, baking powder, espresso powder, and vanilla extract. Mix until well combined.

Step 5

Stir in the flour and chocolate chips until just combined.

Step 6

Spread into prepared pan (batter will be very thick and sticky) and bake for about 30-35 minutes, until a tester comes out mostly clean. The edges should be set and the center should still look slightly moist, but not uncooked.

Step 7

Cool on a wire rack before slicing and serving. Store tightly covered for 3-5 days.